The red K6 telephone kiosk is clearly a classic of good everyday design. A tourist attraction in its own right, it has been a familiar part of the British streetscape since it first appeared in 1936. Designed the previous year by Giles Gilbert Scott (1880-1960), architect of Liverpool's Anglican Cathedral, Waterloo Bridge and Battersea Power Station, the beautifully proportioned K6 is a classically inspired work of architecture in miniature. It even boasts a "pendentive" dome, a happy design reference to the work of Britain's most inventive classical architect, Sir John Soane.

A development of Scott's earlier, and grander, K2 box of 1924, the mass-produced K6 was designed and built to last. Each of the 70,000 kiosks put up on British streets between 1936 and 1968 is made up of three-quarters of a tonne of cast iron, teak (the door frame) and steel (the 200 screws that hold the whole caboodle together). In its lifetime, each has served as a shelter from rainstorms as well as an easily identified place for making telephone calls using different types of equipment as telecommunications technology itself has changed.

Threatened with complete destruction by a churlishly "modernising" British Telecom in the 1980s, the K6 was the object of a high profile and hugely popular conservation campaign. This resulted in the Grade 2 listing of around 2,000 K6s in special locations. Today, some 14,000 survive.

But . . . what exactly are they for in the age of the all but universal mobile phone? Sheltering from the rain? Urinals for yobs? Backdrops for tourist photographs? Advertisement hoardings for sex services? These are some of the roles they play in 2007. What they are increasingly rarely used for is . . . making phone calls. I have to admit that although I think they look terrific, I haven't used one for at least a couple of years.

So, here is a design conundrum. The K6 is a lovely thing, and deserves to remain a part of our 21st-century streetscape, but what can we do to keep them properly, or effectively, in use? Of course they ought to retain vandal-proof phones of some sort or other, especially for emergencies, but perhaps they could also house vending machines and information services that would be especially useful for visitors to an unfamiliar town or city. In homes they are used as shower cabinets, and, elsewhere, they are popular features in museums, theme parks and novelty cocktail bars; but, what could, and should, we do to keep these very special everyday public designs going into the foreseeable future and even beyond? Any suggestions gratefully received by email as you are unlikely to call from a roadside K6.